Clamping or braking devices are known in the most varied embodiments for the most varied application cases. Thus, a braking device of a linear guide is known in published European Patent Application No. EP-A-0936366 that has a supporting body and can be moved along a guide track. The supporting body has brake shoes, which act on the two longitudinal sides. The supporting body is shaped like an H and has a thin, elastically flexible crosslink and two lower legs, with which it grips the guide track. A brake shoe is located between a lower leg and the guide track. The supporting body is provided with two upper legs, which, together, form a holding space with the crosslink, in which a force-producing means, acting on the upper leg, is provided. This can be hydraulically or pneumatically actuatable toggle lever mechanics or a piezoelectric actuator. Moreover, a hydraulically or pneumatically actuatable wedge valve can be provided as a force transducer, which is conducted in a formed space, which tapers in the longitudinal direction of the brake device, between the upper legs of the supporting body. In all cases, a bending of the elastic crosslink takes place due to the force pressurization of the two upper legs, so that the two lower legs are moved inwards with the brake shoes or apply pressure on the guide track with a large force.
The disadvantage with this known brake device, in connection with the use of an electromechanical transducer such as a piezoelectric element, is, in particular, its sensitivity with respect to vibrations or other mechanical loads.
The use of a toggle lever or a wedge valve, just like an electromechanical transducer, means a high installation or production expense.
In addition, there is, in particular with clamping devices, the requirement of sufficiently high clamping forces, which, with known devices, can be implemented only with a relatively high construction and thus financial expense.
From U.S. Pat. No. 5,855,446, a hydraulic clamping bushing is known, which is aligned on a shaft and can be connected to it, for example, in a stationary manner. The bushing essentially has a stable bushing body, which is located at a distance around a drive shaft. Adjacent to these bushing bodies and facing the shaft, a chamber which can be acted on with pressure is provided. A side wall of this chamber, which extends essentially parallel to the shaft is used here, at the same time, as a braking element, which with the action of pressure on the chamber is pressed against the shaft by the expansion of the chamber, in order to produce a friction-locking connection. A Σ-shaped formation of the laterally adjacent walls of the chamber is meant to prevent the bushing from aligning crooked with respect to the wall when the pressure acts on chamber. The Σ-shaped side walls of the chamber make possible, in the case of pressure pressurization, an expansion of these side walls in a radial direction toward the shaft, before the increasing chamber pressure also presses the chamber wall, running parallel to the shaft, against the shaft. Thus, the bushing can be aligned at right angles to the shaft axis, before the tortional connection is produced.
This clamping device does not have a favorable power transmission for the creation of a higher pressing force. Furthermore, in its shape and in particular, in its placement possibility relative to the bushing body, the chamber is limited. The braking effect can be attained here only by acting on the chamber with excess pressure, and the actual braking element, which must perhaps transfer high driving forces, is not firmly connected to the bushing body, but rather only via the inevitably relatively unstable pressure chamber.
From published PCT Patent Application No. WO 01/34990 A1 from the applicant, a clamping and/or braking device is known, in which a chamber which can be acted on with pressure is provided on a basic body; in at least one partial area of at least one deformable or tension-resistant and/or pressure-resistant wall, the chamber is limited. The limitation of the chamber opposite the wall can also be constructed like the first wall. However, it can also be a rigid part of a body. Preferably, the walls lie at a relatively small distance from one another. The forces resulting from the deformation of the chamber are conducted, at least in part, in the direction of or along the wall and in the area of the connection of the wall to a basic body are introduced into the latter. If one selects the point of attack of such forces on the basic body, and if this basic body is, at least partially, elastically deformable, then the forces can be transferred, for example, into the clamping or braking areas via this basic body on other sites of the basic body. A corresponding braking or clamping means in these areas can then be moved, by means of the forces, into a pressurizing position or out of it, so as to brake or release a guide element or an element which has to be clamped or braked. Both applied excess or reduced pressure in the chamber can be used thereby, in order to introduce both tractive and compressive forces to the basic body. Of course, before and after the introduction of force, the clamping and/or braking areas are still engaged with the guide element or the element to be clamped or braked, wherein, however, changes in the pressurizing forces between the clamping and/or braking areas and the other element result.
This known clamping and/or braking device is based on the knowledge that when acted on by a reduced or excess pressure, a suitable chamber tends to a deformation. If this chamber, to a great extent, is formed by at least one approximately plane wall, then the excess or reduced pressure in the chamber first causes a deformation in a first direction running essentially perpendicular to this wall. In order to yield to the deformation (expansion or contraction) in this first direction, the result from this, in a correspondingly reverse manner, is a contraction or expansion of the chamber in a second direction generally running perpendicular to the first direction (that is, essentially parallel to the wall). The fact is used thereby that low forces or deformations in the first direction produce large forces in the second direction, which can be used to brake or clamp or to release pretensioned clamping or braking devices.